From Halopedia, the Halo wiki
Sapphire Three is a Beta-5 Division operative active in the post-war era.
On September 26, 2557, two months after the New Phoenix Incident and Cortana's supposed death, Sapphire Three personally conducted an interview with Master Chief John-117 at Borneo Station, discussing his interactions with his AI companion back in late 2552. She inquired about Cortana's state at the time of her rescue on the Ark and about cryptic messages the Master Chief had experienced while he was lightyears apart from her.
Following the rise of the Created a year later, Sapphire Three provided an excerpt of the interview to 92738-61842-LC of Fireteam Apollo after the latter requested it in their own investigation of Cortana.